Oil lubricants are among the many fluids which are sometimes metered and dispensed during industrial operations. As used herein, "oil(s)," "oil lubricant(s)," and "lubricant(s)" are herein defined to broadly include petroleum-based and synthetically derived fluids which are in the liquid state when metered and dispensed. Accuracy in metering oil is important in that, if too little oil is supplied to a machine or machine parts, the machine may be placed at risk, as by damage caused by excessive friction. Conversely, if too much oil is supplied to a machine or machine parts, the excess oil may adulterate a product or may contribute to localized pollution or safety hazards in the vicinity of a work station. While accuracy in metering is generally desired, it is often difficult to attain. As a general matter, the prior art devices have not operated effectively because ambient air enters the feeding or metering system during lubrication operations and becomes entrapped in a metering chamber. In such prior art devices, the entrapped air in the metering chamber displaces liquid in the measured quantity to render metering in minute quantities virtually impossible, and in larger quantities inaccurate.
Industrial machines require lubrication throughout their operation cycles due to the conditions of the environment. For example, extremely high temperatures cause lubricants, which have been applied to power transmission assemblies, to evaporate or otherwise become displaced therefrom. Additionally, because of the configuration of certain manufacturing facilities or the type of manufacturing process, lubrication assemblies must sometimes be placed in a location remote to the object receiving the lubrication. On such occasions, it is often necessary to shoot or otherwise propel a measured volume of lubricant toward the object of interest requiring lubrication. Further, to meet the requirements and demands of industry to efficiently produce various commercial articles, it is often necessary to dispense and apply metered volumes of other fluids, such as adhesives. For example, hot melt adhesives are often applied to a carrier medium which is typically located a predetermined distance from the adhesive dispensing apparatus.
Heretofore, liquids, such as lubricants and the like, have been dispensed by means of conventional piston pumps which are disposed in fluid communication with a standard nozzle. More particularly, prior art liquid dispensing apparatuses typically employ conventional piston pumps to provide metered pulses of pressurized fluid which are directed through a standard single orifice type nozzle and toward an object of interest for application thereon. However, while widely diverse in construction and operation, prior art liquid dispensing apparatuses are replete with a multiplicity of deficiencies and shortcomings which have detracted from their usefulness.
Foremost among the deficiencies of the prior art liquid dispensing apparatuses is their apparent inability to deliver the entire metered volume of liquid on the object of interest. As should be understood, previously employed nozzles typically generate, in addition to a main stream of liquid, a secondary liquid stream component which is directed away from the object of interest, thereby reducing the volume of liquid received by the object of interest. This secondary liquid stream component is often referred to as "spray" or "tail-off." During a typical liquid dispensing process, the metered volume of liquid separates from the main stream of liquid at a location outside of the nozzle, which results in the production of the secondary liquid stream. Thereafter, gravity and ambient air turbulence work to scatter the spray or tail-off throughout the work environment. This, of course, contaminates the immediate work station, and wastes valuable resources, and often creates unsafe conditions within a manufacturing site.
Still another deficiency of the prior art lubricating devices is their apparent inability to reduce or eliminate drops of liquid which form on, and fall from, the end of the nozzle. When using a conventional piston pump, liquid typically collects at the discharge end of the nozzle following separation of the metered volume of liquid from the main stream of liquid. Over time, gravity acts upon this small collection of liquid drops and causes the drops to fall upon work floors and other work surfaces which are located below the nozzle. In view of this shortcoming, various drip avoidance methods have typically been employed, such as, for example, positioning drip pans immediately below the nozzle. Such drip pans are only marginally effective in reducing unsafe conditions in the workplace created by the dripping of liquids such as lubricants onto work floors and other work surfaces.
Accordingly, a need has arisen for an apparatus for dispensing and applying a liquid on a remote object of interest, wherein the liquid is dispensed in a metered volume which separates cleanly from the main stream of liquid and minimizes the production of a secondary liquid stream, and which substantially eliminates the drip of liquid from the apparatus during the dispensing and application process.